i accidentally stopped my 18.7.1 update for my rx 570, used ddu to clean due to partial installation and then installed again to 18.7.1. after installation, i restarted my pc and the display got unusually too dark and dim. is this normal? if not how do i fix it?

If your were using a custom calibration for color or brightness and contrast settings before and ran DDU it would have deleted those. When you installed the driver it was back at defaults. You just need to set things back to where you want it.